Interleukin-1a (IL-1a) is a multifunctional cytokine that promotes in¯ammation, tissue remodeling and epithelial hyperplasia. Keratinocytes produce and sequester large amounts of biologically active IL-1a which can be released after injury or infection. We show that high level expression of human papillomavirus (HPV) type 16 E6 and E7 oncoproteins enhanced release of IL-1a from cultures of normal cervical keratinocytes (relative eectiveness E74E6/E7>E64 control). The amount of IL-1a released was directly related to the ability of E7 or E6/E7 to stimulate apoptosis. E7 proteins that bound the retinoblastoma protein (Rb) strongly (HPV-16 and -18) induced more IL-1a release than those that bound poorly (HPV-6 and an HPV-16 E7 24gly mutant). Furthermore, overexpression of the E2F-1 transcription factor, a downstream target of Rb, induced extensive apoptosis and IL-1a release. Apoptosis and IL-1a release in response to growth factor removal occurred in part through a p53-independent pathway as coexpression of E6 and downregulation of p53 did not prevent either response. Immunohistochemical analyses showed that IL1a was expressed by keratinocytes in normal cervical epithelia, low and high grade dysplasias, and cervical carcinomas. However, HPV-16 E6/E7 RNA expression and apoptosis increased in parallel in proliferating keratinocytes in severe dysplasias and carcinomas suggesting that IL-1a release is associated with progression to high grade disease. Thus, high level expression of the HPV-16 E7 protein sensitizes keratinocytes to apoptosis which results in release of IL-1a.

Tumor necrosis factor-alpha (TNF-alpha) inhibits growth of normal cervical keratinocytes but stimulates proliferation of human papillomavirus (HPV)-immortalized and cervical carcinoma-derived cell lines when mitogens such as epidermal growth factor (EGF) or serum are depleted. Current work identifies the mechanism of growth stimulation. TNF-alpha promoted cell cycle progression by increasing expression of HPV-16 E6/E7 RNAs and enhancing activity of cyclin-dependent kinase (cdk)2 and cdc2 after 3 d. Increased kinase activity was mediated by upregulation of cyclins A and B and decreases in cdk inhibitors p21(waf) and p27(kip). TNF-alpha stimulated these changes in part by increasing transcription and stabilization of RNA for amphiregulin, an EGF receptor ligand, and amphiregulin directly increased HPV-16 E6/E7 and cyclin A RNAs. To define which components of the EGF receptor signaling pathway were important, HPV-immortalized cells were transfected with activated or dominant negative mutants of Ha-ras, raf, or MAPKK. Expression of activated Ha-ras maintained HPV-16 and cyclin gene expression and promoted rapid growth in the absence of EGF. Furthermore, ras activation was necessary for TNF-alpha mitogenesis as transfection with a dominant negative ras mutant (Asn-17) strongly inhibited growth. Thus, activation of ras promotes expression of HPV-16 E6/E7 RNAs, induces cyclins A and B, and mediates growth stimulation of immortal keratinocytes by TNF-alpha. These studies define a pathway by which ras mutations, which occur in a subset of cervical cancers, may contribute to pathogenesis. Mol. Carcinog. 27:97-109, 2000. Published by Wiley-Liss, Inc.